420 research outputs found
Hydrochemistry measured on water bottle samples during Mohamed Sedik Benyahia cruise MEDAR/ANDRU/ISMAL
No full textHydrochemistry measured on water bottle samples during Mohamed Sedik Benyahia cruise MEDAR/ANDRU/ISMA
Lack of BV bounds for approximate solutions to a two-phase transition model arising from vehicular traffic
No full textWe consider wave-front tracking approximate solutions (Formula presented.) to a two-phase transition model for vehicular traffic. We construct an explicit example showing that the total variation in space of (Formula presented.) may blow up in finite time for (Formula presented.) even for an initial datum with bounded total variation
Sustainability and Techno-Economic Assessment of Batch and Flow Chemistry in Seven Industrial Pharmaceutical Processes
No full textThe synthesis of active pharmaceutical ingredients (APIs) is commonly perceived as more efficient when performed using continuous-flow methods, whereas batch processes are often seen as less favorable due to their limitations in yield, heat and mass transfer, and safety. This perception largely stems from existing studies that focus on green metrics such as the E-factor and yield. However, a comprehensive comparison of batch and flow processes through full techno-economic analyses (TEA) and life-cycle assessments (LCA) remains underexplored, leaving key aspects of their environmental and economic impacts inadequately assessed. This work addresses this gap by presenting a detailed comparison of batch and flow syntheses of seven industrially relevant APIs, including amitriptyline hydrochloride, tamoxifen, zolpidem, rufinamide, artesunate, ibuprofen, and phenibut. Eleven environmental impact categories within the framework of nine planetary boundaries were assessed, and the study also included an evaluation of capital and operating costs for both production methods. The results demonstrated that, on average, continuous-flow processes are significantly more sustainable with improvements in energy efficiency, water consumption, and waste reduction. Flow processes also show a marked reduction in carbon emissions and up to a 97% reduction in energy consumption, highlighting their potential for greener API manufacturing. Despite these advantages, the study identified areas where the continuous-flow technology requires further development. Specifically, manufacturing certain APIs in flow show lower-than-average improvements in operating expenditure and land system changes, the latter being directly correlated with the consumption of organic solvents, that can be comparable to or even higher than in batch. These challenges highlight the need for further optimization of flow processes to fully realize their potential in API production
General phase transition models for vehicular traffic with point constraints on the flow
No full textIn this paper, we present a general phase transition model that describes the evolution of vehicular traffic along a one-lane road. Two different phases are taken into account, according to whether the traffic is low or heavy. The model is given by a scalar conservation law in the free-flow phase and by a system of 2 conservation laws in the congested phase. The free-flow phase is described by a one-dimensional fundamental diagram corresponding to a Newell-Daganzo type flux. The congestion phase is described by a two-dimensional fundamental diagram obtained by perturbing a general fundamental flux. In particular, we study the resulting Riemann problems in the case a local point constraint on the flow of the solutions is enforced
Assessing Grapevine Water Status by Integrating Vine Transpiration, Leaf Gas Exchanges, Chlorophyll Fluorescence and Sap Flow Measurements
No full textA precise knowledge of the grapevine responses to increasing level of water stress is of the utmost relevance for an effective application of deficit irrigation strategies in viticulture. Against this background, a study was conducted on potted grapevines subjected to two ten-day drought cycles to assess their water status by integrating the information derived from different physiological indexes including whole-plant transpiration (measured gravimetrically and with sap flow sensors), leaf gas exchanges and chlorophyll fluorescence. When soil water availability was not limited, vine transpiration rate was determined mainly by environmental factors and ranged between 0.5 and 2 L day−1 m−2 of leaf surface. Transpiration was affected by the soil water availability only when water stress became evident (midday stem water potential < −1 MPa), with vines showing a strong limitation of the stomata functioning (stomatal conductance < 0.05 mol m−2 s−1) and, consequently, low transpiration rates (<0.5 L m−2 d−1). Transpiration rates measured with the sap flow sensors were correlated with those measured gravimetrically, showing daily patterns that were highly affected by the intensity of the water stress. Nevertheless, these sensors highly underestimated actual transpiration rates, limiting their reliability for vineyard irrigation management. At the end of the second drought cycle, vines showed very limited responses to daily changes in environmental conditions (same photosynthetic rate and stomatal conductance at morning, midday and afternoon), likely reflecting a carryover stress effect from the first drought cycle and an incomplete physiological recovery before the beginning of the second. Evidence of the severe water stress reached by vines was also given by the high value of the quantum yield of nonregulated energy dissipation (Y(NO) higher than 0.4) found at the end of the first drought cycle. Taken together, the obtained results integrate the current knowledge on water stress development in grapevine, also highlighting the relevance of specific physiological indexes that could be used effectively for the correct management of deficit strategies in viticulture
Hydrochemistry measured on water bottle samples during Mohamed Sedik Benyahia cruise MEDPOL III/FEM/ISMAL
No full textImproving Control Performance by Cascading Observers: Case of ADRC With Cascade ESO
No full textIn this paper, we show the performance benefits of connecting multiple observers within a control system. We focus here on a particular observer-based control approach, namely the active disturbance rejection control (ADRC) with cascade extended state observer (ESO). For this framework, we analyze the control performance in terms of quality of observer estimation, reference tracking, disturbance rejection, sensitivity to measurement noise/unmodeled dynamics, and overall stability. A comprehensive frequency response analysis is performed to study the influence of cascading the observers on the selected quality criteria. To make the inquiry beneficial also to practitioners, FPGA-in-the-loop tests are conducted using a guided missiles gimbaled seeker. They validate the theoretical findings in discrete-time settings, where the sampling time and hardware resource requirements become a factor. The results of the investigation are distilled into guidelines for prospective users on when and how a cascade observer structure can be useful for controls.
A Hierarchical Bayesian Model for Frame Representation
No full textIn many signal processing problems, it is fruitful to
represent the signal under study in a frame. If a probabilistic approach is adopted, it becomes then necessary to estimate the hyperparameters characterizing the probability distribution of the frame coefficients. This problem is difficult since in general the frame synthesis operator is not bijective. Consequently, the frame
coefficients are not directly observable. This paper introduces a hierarchical Bayesian model for frame representation. The posterior distribution of the frame coefficients and model hyperparameters is derived. Hybrid Markov chain Monte Carlo algorithms are subsequently proposed to sample from this posterior distribution. The
generated samples are then exploited to estimate the hyperparameters and the frame coefficients of the target signal. Validation experiments show that the proposed algorithms provide an accurate estimation of the frame coefficients and hyperparameters. Application to practical problems of image denoising in the presence of uniform noise illustrates the impact of the resulting Bayesian estimation on the recovered signal quality
Conception et réalisation de rover en matériaux composite M Rover 12
No full textLa majorité des robots, en particulier ceux utilisés dans l’industrie, sont immobiles. Ces dernières années beaucoup d'attention a été concentrée sur le succès des robots mobiles. Aujourd'hui, le marché commercial de la robotique mobile est toujours relativement restreint. Les applications de ses robots peuvent se trouver dans de nombreuses activités 'épuisantes, salissantes ou dangereuses', mais également pour des applications ludiques ou de service, comme l'assistance aux personnes âgées ou handicapées. L’application visée est la validation d’une conception et sa fabrication en utilisant des matériaux composites comme base du robot mobile. Nous décrivons de manière formelle la structure complète du robot mobile. Cette synthèse aborde l’interaction entre le robot mobile et un partenaire humain distant ou partageant son environnement dans le cadre de la robotique d’assistance à la personne. Une telle interaction s'exprime pleinement dans des situations où l'homme et le robot doivent agir en collaboration pour réaliser une tâche où ils partagent l'espace de travail et se perçoivent directement. Le succès d’un robot mobile dépend principalement de la bonne adéquation de la plate forme mobile à la stratégie globale que nous avons déterminé. Dans ce travail, quatre aspects fondamentaux de l’étude, conception, fabrication et validation de la base mobile en matériaux composite (polyptère, tissu) du prototype du robot mobile seront abordés. En effet, que ce soit pour un seul individu ou pour toute une équipe, se lancer dans la conception et la réalisation d'un robot est toujours un défi
Reliability and Importance Measures for Combined m-Consecutive-k-Out-of-n: F and Consecutive-kb-Out-of-n: F Systems with Non-Homogeneous Markov-Dependent Components
No full text A Combined [Formula: see text]-Consecutive-[Formula: see text]-out-of-[Formula: see text] and Consecutive-[Formula: see text]-out-of-[Formula: see text]: F System consists of [Formula: see text] components ordered in a line such that the system fails iff there exist at least [Formula: see text] consecutive failed components, or at least [Formula: see text] nonoverlapping runs of [Formula: see text] consecutive failed components, where [Formula: see text]. This system was been introduced by Mohan et al. [P. Mohan, M. Agrawal and K. Sen, Combined [Formula: see text]-consecutive-[Formula: see text]-out-of-[Formula: see text]: F and consecutive-[Formula: see text]-out-of-[Formula: see text]: F systems, IEEE Trans. Reliab. 58 (2009) 328–337] where they propose an algorithm to evaluate system reliability by using the (GERT) technique, in the independent case. In this paper, we propose a new formula of the reliability of this system for nonhomogeneous Markov-dependent components. For a Combined [Formula: see text]-Consecutive-[Formula: see text]-out-of-[Formula: see text] and Consecutive-[Formula: see text]-out-of-[Formula: see text]: F System with nonhomogeneous Markov-dependent components, we derive closed-form formulas for the marginal reliability importance measure of a single component, and the joint reliability importance measure of two or more than two components using probability generating function (pgf) and conditional pgf methods. </jats:p
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